Liquid bandages have become popular in recent years because of their ease of use in topical applications of protecting skin and/or of preventing damage to skin by forming conformal, topical coatings. Such applications have been from polymer coatings that are delivered from soluble solutions in volatile solvents including non-stinging solvents to skin and open wounds, such as hexamethyldisiloxane (HMDS), and isooctane (2,2,4-trimethylpentane), as well as stinging alcohol-based solvents, such as isopropanol and ethanol, for inherent antimicrobial character and the potential to solubilize many antimicrobial agents. While such polymer coatings are typically water insoluble, other coatings can be delivered from water utilizing water-soluble polymers and which, consequently, will redissolve in water.
Alkylsiloxysiloxane-containing hydrophobic polymers have been admixed with liquid polydimethylsiloxanes (U.S. Pat. No. 5,103,812 and U.S. Pat. No. 4,987,893) to provide non-stinging, non-irritating coating materials that allow body fluid evaporation and oxygen permeability while protecting the body surface from further contamination and desiccation. In another variation, alkylsiloxysiloxane-containing polymers were admixed with 2,2,4-trimethylpentane to provide similar non-stinging coating properties (U.S. Pat. No. 6,383,502). These coatings have the common disadvantages of loss of adhesion toward hydrated surfaces, loss of adhesion in higher flexibility areas such as knuckles or knees, and being adherent surfaces to themselves or other objects at room temperature or body temperature. The primary alkylsiloxysilane monomer for these polymer coatings has been 3-methacryloyloxypropyltris(trimethylsiloxy)silane (TRIS, also known as 3-[tris(trimethylsiloxoy)silyl]propyl methacrylate).
A major difficulty with such coatings that has not been addressed has been their adhesion to undergarments, bed clothes, sheets, blankets, tubing, medical devices and dressings, as well as attachment to more than one portion of one's body, such as a folded arm, a folded leg, under a chin, or under a breast. When heated to body temperature, such coatings adhere to skin and to surfaces with which the polymer coated skin is in contact. In combination with external body temperature (33-37° C.) and pressure applied to different portions of the body, the air surface of the polymer coating can fold and adhere to itself, causing discomfort. In particular, if an individual is confined to bed and has limited mobility, the pressure of lying in one place for extended periods of time, combined with high shear forces when the person is raised or lowered on the bed, sliding against the bed sheets, the liquid bandage can adhere to the bed sheets and hence cause damage, particularly to fragile skin and wounds. This feature is a result of sustained pressure, friction, and shear. A similar problem can occur with medical devices where friction, pressure and shear forces can cause discomfort to a patient with movement.
As used herein, “medical device” has its plain meaning and includes objects whose surfaces contact skin, tissue, blood or other bodily fluids and components, as well as materials, such as sutures, needles, sheets, bed clothes, pillows, undergarments, blankets, cushions, towels, tubing, membranes, and the like, wherein such medical devices include, but are not limited to, catheters, such as dialysis catheters, central venous catheters, thoracic drain catheters, urinary catheters, and angioplasty balloon catheters; surgical implants, such as coronary stents; and prostheses, such as artificial limbs. Examples of suture materials include poly(glycolic acid), poly(lactic acid), poly(lactic-co-glycolic acid), polydioxanone, polycaprolactone, poly(3-hydroxybutyrate), silk, catgut, collagen, cotton, nylon, polyester, polypropylene, leather, and combinations thereof. Examples of tubing include tubing used with catheters and in intravenous or intra-arterial infusion and other surgical uses, as well as in whole blood oxygenators, and the like. Examples of membranes include hemodialysis membranes, blood oxygenation membranes, artificial pancreas membranes, and membranes used in diagnostic and biosensor devices. Examples of fabrics, such as clothes, sheets, blankets, towels, etc., are often composed of cotton, nylon, polyester, wool, nonwoven materials, polyethylene, polypropylene, combinations thereof, and biodegradable materials.
Additional medical devices include sponges, staples, tapes, clamps, leads, lead adapters, lead connectors, clips, covers, drapes, blood filters, temperature monitors, cannulae, implantable pumps, ostomy pouches, dialyzers, drainage products, electrodes, stethoscopes, fracture fixation devices, gloves, guide wires, pins, retention cuffs, screws, ceramics, biodegradable polymers, bioglass, poly(methyl methacrylate) materials, polyethylene materials, elastomers, surgical instruments, valves, balloons, batteries, orthopedic implants, pacemakers, plugs, plates, ports, prosthetic heart valves, shunts, and vascular access devices.
When a non-stinging application to a biological surface is not required, such as treating skin in areas prior to blister formation, such products can be alcohol based. A prominent example is New-Skin® Liquid Bandage from Prestige Bands, Inc., which contains an ester solvent (amyl acetate), an alcohol solvent (ethanol) that is also antimicrobial, a film forming polymer of nitrocellulose, a propellant of isooctane-propane, oils for lubricating and other health benefits, and added antimicrobial agents of benzethonium chloride and benzalkonium chloride.
A related liquid bandage product when a non-sting application is not preferred is Curad® Spray Bandage by Beiersdorf AG, composed of a film forming polymer of poly(methyl acrylate-isobutene-monoisopropyl maleate), in ethyl acetate, n-pentane, carbon dioxide, and menthol.
Another category of polymer useful as a liquid adhesive bandage, cycloalkyl methacrylate copolymers, has been found to be soluble in a mixture of liquid polydimethylsiloxanes, 2,2,4-trimethylpentane and isododecane (U.S. Pat. No. 6,358,503).
Cyanoacrylates have also found use as liquid adhesive bandages, particularly butyl and octyl cyanoacrylates (U.S. Pat. No. 6,183,593; U.S. Pat. No. 6,143,805). These materials provide quick film formation and are especially useful for closing thin wounds, such as those created by paper or razor cuts. Wounds that are in high flex areas are not suitable for treatment with cyanoacrylates as they tend to increase scarring, if well adhered, or to delaminate quickly, if not well adhered due to their intrinsic brittleness.
Water-soluble liquid bandages are also available for human, veterinary, and device use, such as JUC Liquid Bandage Spray from NMS Technologies that forms a positively charged antimicrobial coating. Another water-soluble liquid bandage, for veterinary use only, is Facilitator from IDEXX Pharmaceuticals, which is composed of water-soluble hydroxyethyl starch. A variety of poly(N-vinylpyrrolidone) water-based liquid bandages are also available for veterinary use. Whereas water-based liquid bandages are normally less traumatic when applied to an open wound than application of an organic solvent, the drying time of a polymer film deposited from water can be long, and it therefore may be difficult to form a polymer coating in a desired location because of water flow.
An antimicrobial coating composition for devices selected from the group of alkyl acrylates, alkyl methacrylates, alkyl hydroxyl(meth)acrylates, and alkyl methoxycinnamate acrylates has been reported in a mild solvent, including alcohols and hydrocarbons (U.S. Pat. Appl. 2010/0137472), wherein the coatings can be applied at 60° C. for 10 minutes or less.
Water- and alcohol-based liquid bandages also have the capability of solubilizing antimicrobial agents and active pharmaceutical agents, such that when a polymer coating is cast, the active agent is encapsulated within a polymer film, resulting in a sustained (controlled) release of the biologically active agent over time. Many such biological agents are often polar compounds and/or can be in salt form, facilitating solubility in polar solvents.
The use of alcohol-based solvents for liquid bandages containing an antimicrobial agent enhances the overall antimicrobial activity because of the innate biocidal behavior of alcohol solutions, primarily ethanol and isopropanol, particularly in the presence of water, wherein the water may emanate from added water to the liquid bandage solution, moisture in/on the skin or wound, moisture from the air, or from standing or moving water, such as from pools, rain, lakes, streams, rivers, tributaries, bays, oceans, and the like, wetting the skin, mucosal tissue, and, potentially, open wounds.
The addition of antimicrobial agents to coatings from liquid bandages has great importance in controlling infection and the deposition and growth of microorganisms in burns, in acute and chronic wounds, on surfaces of medical devices and dressings, in pre- and post-surgical coatings, and in all areas of the body where microorganisms can propagate.